In an IP mobile bearer network, that is, a mobile packet bearer network, in order to save a radio resource and reduce power consumption of a user equipment, when the user equipment (User Equipment, abbreviated as UE) has no service interaction (that is, signaling interaction and user plane data transmission) with the network for a period of time (for example, 30 seconds), the network releases a signaling connection and a user plane bearer between a radio interface side and the UE, and at this time, the UE is in an idle state (Idle State); when the UE needs to send or receive user plane data, the UE first recovers a signaling connection with the network, recovers a user plane bearer through the signaling connection, and sends or receives the user plane data through the recovered user plane bearer, and at this time, the UE is in a connected state (Connected State).
However, because some services of small data volumes, for example, short message service (Short Message Service, abbreviated as SMS), only need to transmit a few user plane IP data packets carrying SMS content each time, the UE in the idle state, when implementing the services of small data volumes, needs to perform a corresponding signaling process each time to establish (recover) a radio interface side user plane bearer, that is, a radio access bearer (Radio Access Bearer, abbreviated as RAB), which increases the signaling overhead, thus increasing the network load and the operating cost of an operator.